Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee Harrison asks if the enclosed appendix addressing the points raised by Callendar on Dugald Clerk's paper 'On the specific heat of, heat flow from, and other phenomena of, the working fluid in the cylinder of the internal combustion engine' should be printed in Proceedings of the Royal Society, as an addendum to the full paper. 26 March 1906